<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes" />
    <title>ShellCheck: SC2295 – Expansions inside `${..}` need to be quoted separately, otherwise they will match as a pattern.</title>
    <link rel="stylesheet" href="css/bootstrap.min.css" />
  </head>
  <body style="margin-left: auto; margin-right: auto; max-width: 800px">
    <h1>SC2295 – ShellCheck Wiki</h1>
    <a href="https://github.com/koalaman/shellcheck/wiki/SC2295">See this page on GitHub</a>
    <p style="display: none"><a href="index.html">Sitemap</a></p>
    <hr />
    <h2
id="expansions-inside--need-to-be-quoted-separately-otherwise-they-will-match-as-a-pattern">Expansions
inside <code>${..}</code> need to be quoted separately, otherwise they
will match as a pattern.</h2>
<h3 id="problematic-code">Problematic code:</h3>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC2295.html#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="fu">relative_path()</span> <span class="kw">{</span></span>
<span id="cb1-2"><a href="SC2295.html#cb1-2" aria-hidden="true" tabindex="-1"></a>  <span class="bu">printf</span> <span class="st">&#39;%s\n&#39;</span> <span class="st">&quot;</span><span class="va">${2</span><span class="op">#</span><span class="va">$1}</span><span class="st">&quot;</span></span>
<span id="cb1-3"><a href="SC2295.html#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="kw">}</span></span>
<span id="cb1-4"><a href="SC2295.html#cb1-4" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb1-5"><a href="SC2295.html#cb1-5" aria-hidden="true" tabindex="-1"></a><span class="co"># Results in &quot;/tmp/King_Kong_[1933]/extras/trailer.mkv&quot; because the prefix fails to match</span></span>
<span id="cb1-6"><a href="SC2295.html#cb1-6" aria-hidden="true" tabindex="-1"></a><span class="ex">relative_path</span> <span class="st">&quot;/tmp/King_Kong_[1933]/&quot;</span> <span class="st">&quot;/tmp/King_Kong_[1933]/extras/trailer.mkv&quot;</span></span>
<span id="cb1-7"><a href="SC2295.html#cb1-7" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb1-8"><a href="SC2295.html#cb1-8" aria-hidden="true" tabindex="-1"></a><span class="co"># Results in &quot;cover.jpg&quot; even though the prefix is different</span></span>
<span id="cb1-9"><a href="SC2295.html#cb1-9" aria-hidden="true" tabindex="-1"></a><span class="ex">relative_path</span> <span class="st">&quot;/tmp/King_Kong_[1933]/&quot;</span> <span class="st">&quot;/tmp/King_Kong_3/cover.jpg&quot;</span></span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC2295.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="fu">relative_path()</span> <span class="kw">{</span></span>
<span id="cb2-2"><a href="SC2295.html#cb2-2" aria-hidden="true" tabindex="-1"></a>  <span class="bu">printf</span> <span class="st">&#39;%s\n&#39;</span> <span class="st">&quot;</span><span class="va">${2</span><span class="op">#</span><span class="st">&quot;</span><span class="va">$1</span><span class="st">&quot;</span><span class="va">}</span><span class="st">&quot;</span></span>
<span id="cb2-3"><a href="SC2295.html#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="kw">}</span></span>
<span id="cb2-4"><a href="SC2295.html#cb2-4" aria-hidden="true" tabindex="-1"></a><span class="co"># Results in &quot;extras/trailer.mkv&quot; as expected</span></span>
<span id="cb2-5"><a href="SC2295.html#cb2-5" aria-hidden="true" tabindex="-1"></a><span class="ex">relative_path</span> <span class="st">&quot;/tmp/King_Kong_[1933]/&quot;</span> <span class="st">&quot;/tmp/King_Kong_[1933]/extras/trailer.mkv&quot;</span></span>
<span id="cb2-6"><a href="SC2295.html#cb2-6" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb2-7"><a href="SC2295.html#cb2-7" aria-hidden="true" tabindex="-1"></a><span class="co"># Results in &quot;/tmp/King_Kong_3/cover.jpg&quot; as expected</span></span>
<span id="cb2-8"><a href="SC2295.html#cb2-8" aria-hidden="true" tabindex="-1"></a><span class="ex">relative_path</span> <span class="st">&quot;/tmp/King_Kong_[1933]/&quot;</span> <span class="st">&quot;/tmp/King_Kong_3/cover.jpg&quot;</span></span></code></pre></div>
<h3 id="rationale">Rationale:</h3>
<p>When using expansions in a parameter expansion prefix/suffix
expression, the expansion needs to be quoted separately or it will match
as a pattern. The quotes around the outer parameter expansion does not
protect against this.</p>
<p>This means that any variable that contains e.g. brackets, asterisks
or question marks may not match as expected. In the example,
<code>[1933]</code> was interpreted as a pattern character range and
would therefore match <code>/tmp/King_Kong_3/</code> but not
<code>/tmp/King_Kong_[1933]/</code> as was the intention.</p>
<h3 id="exceptions">Exceptions:</h3>
<p>If you wanted to treat the string as a pattern, such as
<code>suffix=".*"; file="${var%$suffix}";</code> then you can <a
href="ignore.html">ignore</a> this suggestion.</p>
<h3 id="related-resources">Related resources:</h3>
<ul>
<li>Help by adding links to BashFAQ, StackOverflow, man pages, POSIX,
etc!</li>
</ul>
    <hr />
    <p style='font-size: 80%'><a href="../index.html">ShellCheck</a> is a static analysis tool for shell scripts. This page is part of its documentation.</p>
  </body>
</html>


